Hinges of this type have existed on the market for some time, and can be employed in industrial equipment, in particular for connecting bonnets, access doors, or the like to the frame of a casing of a machine containing the equipment, in cases wherein access to the inside of the casing is particularly dangerous when the same is running. Similarly, this kind of device may be used for ordinary access doors, for example, to signal the entry or exit of people.
For example, a hinge of this type, arranged on the bonnet or access door of a machine casing, is manufactured so that opening the bonnet causes the actuation of an electric switch suitably installed in the hinge body, which is then capable of issuing an opening signal, or of possibly stopping instantly the power supply to the machine motor, causing the machine to stop. It can thereby be ensured that the operator does not access the machine while the same is running. Similarly, in case of an access door, the safety switch actuates a bell, or another warning system.
For the sake of description simplicity, the term “door” will be used in the following to describe the movable part of the system whereon the hinge is mounted, regardless of it actually being a door of a piece of furniture, or of a car bonnet, or any other closing door of a compartment.
A hinge device of this type is described for example in patent EP 1,239,496 in the name of Bernstein, filed on 2 Feb. 2002. It consists of a 2-flap hinge, wherein one of the two flaps is shaped as a box-like body incorporating a switch system. This system may be operated through a control lever actuated by the rotation of one hinge flap with respect to the other.
More precisely—and as is evident from the examination of patent EP 1,239,496—within said box-like body forming a first hinge flap there is housed a microswitch, whose operation button is controlled by one end of said control lever, whose other end is pivoted in a fixed point of the box-like body, having a fulcrum function. A pin projecting from an intermediate position of the lever engages with a slot obtained in a member integral with the second hinge flap, under the action of a thrust spring. Said member integral with the second hinge flap is the same pin for the mutual rotation of the two hinges. When—due to the effect of the rotation of a hinge flap with respect to the other, during the hinge-supported door opening phase—said pin is pushed out of its slot, the control lever oscillates and operates said microswitch, which issues an electric warning signal of the door opening.
As can be understood, this arrangement has at least one important drawback: as a matter of fact, its construction is relatively complex—also in connection with the need to provide an adjustment system of the maximum width of the door opening angle, for which no warning signal is generated yet—and consequently costly, being easily damaged and necessarily requiring installation and maintenance by skilled staff.
It must also be pointed out that the above-described hinge is necessarily manufactured of a far greater size and with different, or differently-positioned, anchoring means with respect to those of normally-sold switch-less hinges. As can be understood, this represents a remarkable inconvenience in itself in all those cases in which it is necessary to install such a switch hinge as a replacement of a first conventional hinge, because in general there is no sufficient room nor coincidence of the anchoring points.
Moreover, in the majority of cases, this type of hinge is manufactured of a sturdy metal material—in order to supply the microswitch contained in the box-like body with sufficient protection from the deformations resulting from strong stresses on the doors—which becomes expensive.
The object of the present invention is to provide a hinge equipped with a switch which overcomes the disadvantages of the prior art. In particular, it is intended to provide an easy-to-install hinge, which is compact and allows full opening of the doors. A further object is to provide a hinge with a switch which may easily replace switch-less hinges which have been previously installed on the machine.
Yet another object is to obtain a hinge which cannot easily fall prey to acts of vandalism.